4,4-Methylenebis (2,6-diaralkylphenols

ABSTRACT

A new series of compounds having the following formula is disclosed:   WHEREIN R1, R2, R3, and R4 are aralkyl with the proviso that the aralkyl group contains no branching on the carbon alpha to the phenylene group, said compounds useful to stabilize organic materials normally tending to undergo oxidative deterioration.

Brindell et a1.

[ 1 4,4- METHYLENEBIS (2,6-DIARALKYLPHENOLS [75] Inventors: Gordon D. Brindel], Crystal Lake;

Rudy F. Macander, Cary, both of 111.

[73] Assignee: The Quaker Oats Company,

Barrington, 111.

[22] Filed: Mar. 11, 1974 [21] Appl. No.: 449,651

Related U.S. Application Data [62] Division of Ser, No. 253,342, May 15, 1972, Pat No.

[52} U.S. Cl 260/613 R [51] Int. Cl. C071: 43/20 [58] Field of Search 260/613 R [56] References Cited UNITED STATES PATENTS 3,067,259 12/1962 Bailey 260/613 R 3,476,814 11/1969 Meltsher 260/613 R 3,484,218 12/1969 Braxton et a1. 260/613 R X 3,522,318 7/1970 Ashton et a1 260/613 R [4 1 May 13, 1975 Primary Examiner-Bernard Helfin Altorney, Agent, or Firm-Grace .l. Fishel; Joseph P. OHalloran [57] ABSTRACT A new series of compounds having the following formula is disclosed:

n n 0% c11 on wherein R,, R R and R are aralkyl with the proviso that the aralkyl group contains no branching on the carbon alpha to the phenylene group, said compounds useful to stabilize organic materials normally tending to undergo oxidative deterioration.

3 Claims, No Drawings 4,4-METHYLENEBIS (2,6-DIARALKYLPHENOLS This is a divison, of application Ser. No. 253,342, filed May 15, 1972 and now US. Pat. No. 3,8l6,544.

BACKGROUND OF THE INVENTION l. Field of the Invention:

This invention relates to a new class of antioxidants.

2. Description of the Prior Art:

In US. Pat. No. 3,227,678, the patentee disclosed a class of phenolic compounds having the following formula as stabilizers for polypropylene:

a R nog@ cu gon (Formula I) n n wherein R is a lower alkyl group having l to 6 carbon atoms, which may be primary, secondary, or tertiary.

Typical of those compounds were 4,4 methylenebis(2,6-dimethylphenol), 4,4- methylenebis(2,6-diisopropylphenol), and 4,4-

methylenebis( 2,6-di-tert-butylphenol SUMMARY OF THE INVENTION The purpose of the present invention is to disclose and claim a class of phenolic compounds which are unexpectedly good antioxidants for polyolefins.

The present invention may be briefly described as a phenolic compound having the following structural formula:

R1 R3 no-3 cu g-0a (Formula 11) wherein R, R R and R are aralkyl with the proviso that the aralkyl groups contain no branching on the carbon alpha to the phenylene group.

By aralkyl in Formula ll we are to be understood to mean a group of the following structure:

l 1,, (Formula III) wherein X is hydrogen, alkyl, alkoxy, or halogen, and n is an integer between and 5. We prefer that the aral' kyl group contains less than carbon atoms. Where the aralkyl group is substituted with halogen, the halogen group may be chloro, bromo, iodo or fluoro for example. Where the aralkyl group is substituted with alkyl or alkoxy groups, these groups preferably contain from 1 to 13 carbon atoms which may be straight or branched chain. Suitable aralkyl groups include the fol lowing as long the above mentioned proviso is satisfied: benzyl, ar-chlorobenzyl, ar-bromobenzyl, ariodobenzyl, ar-tluorobenzyl, ar-methoxybenzyl, arethoxybenzyl, ar-methylbenzyl, ar-ethylbenzyl, or arterbbutylbenzyl.

Examples of specific phenolic compounds within the scope of Formula ll and useful in the practice of this invention are the following: 4,4'-methylcnebis(2,6- dibcnzyl-phenol 4,4'-methylencbis[ 2,6-di(pchlorobenzyhphenol]; 4,4'-methylenebis[2,6-di(ochlorobenzyl )phenol I; 4,4'methylenebis[2,6-di( p- 4,4'-methylenebisl 2,6-di( p- 4,4'-methylenebis[2,6-di(pmethoxybenzyhphenol]; 4,4-methylenebis[2,6-di(oethoxybenzyl )phenol and 4,4 methylenebis[ 2,6-di( m-methylbenzyl )phenol The phenolic compounds of Formula ll are prepared according to methods well known in the art by reacting formaldehyde with a phenol of the following formula:

wherein R and R are defined consistant with the R R R and R groups in formula ll. Exemplary of such methods is that described in U.S. Pat. No. 2,944,086. All of the suitable phenols are commercially available or prepared by known techniques.

The 4,4'-methylenebis(2,6-diaralkylphenols) of our invention are useful as antioxidants for organic materi als normally tending to undergo oxidative deterioration. By organic material normally tending to undergo oxidative deterioration, we mean to include material based in whole or in part on a skeleton comprising interconnected carbon atoms which upon exposure to oxygen or air loses its desirable properties and becomes weak, brittle, cracked, discolored, viscous or the like. Exemplary organic materials are polymers; hydrocarbon liquids, particularly gasoline and lubricating or fuel oils, hydrocarbon solids or semi-solids, such as waxes, greases and the like; elastomers, such as natural and synthetic rubber; and feeds or foodstuffs.

Typical polymers include polyolefins, polyurethanes, polyethers, and polyamides. Suitable polyolefins include for example, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinyl butyral, polymethyl acrylate, ethylene vinyl acetate copolymers, and ethylene propylene terpolymers. Suitable polyethers include for example polyformaldehyde and polytetramethylene ether glycol.

Hydrocarbon liquids stabilized by our novel tetraphenolic derivatives include motor lubricating oils, gear and transmission fluids based on hdyrocarbon oils, and the like. Fuel oils, such as furnace oils and light kerosene fractions, including gas turbine fuels, are also stabilized by our compositions.

Solid or semi-solid hydrocarbons, such as wax and grease, are also improved by incorporation therein of the tetraphenolic compounds of this invention.

Such solid polymeric elastomers as natural and synthetic rubber are stabilized against hardening, crack ing, and checking with the tetraphenolic derivatives described. Exemplary of natural rubbers is Hevea brasiliensis, while synthetic rubbers include styrenebutadiene rubber; polybutadiene; polyisoprene', neoprene; butyl rubber; nitrilebutadiene rubbers, styrene chloroprene rubbers; acrylatebutadiene rubbers; and polyurethane rubber.

The 4,4-methylenebis(2,6-diaralkylphenols) of this invention are also useful to enhance the stability of the natural fats and oils. For example, the following edible oils can be stabilized with our compositions: shortening, lard, butter, coconut oil, cotton seed oil, soybean oil. palm oil, corn oil, peanut oil. sunflower seed oil, safflower oil, olive oil, and the like or mixtures thereof. These oils may have been treated, as by hydrogenation,

methylbenzyl )phenol ethylbenzyl )phenol (Formula IV) intersterification, or fractional crystallization, to modify their melting points.

The 4,4-methylenebis(2,6-diaralkylphenols) of Formula ll are particularly useful with polymers derived from monoolefins having a terminal double bond. Examples of such alpha polyolefins include but are not limited to the following: polyethylene. polypropylene, poly-4-methylpentenel, polyl-butene, poly-3- methylbutene-l, and copolymers thereof.

In general, the phenolic compound of Formula ll should be used with organic material in an amount effective and sufficient to stabilize the material. The requisite amount will, of course, depend both on the efficiency of the particular phenolic compound and the nature of the organic material to be stabilized. It has been our experience that from 0.01 percent to percent by weight based on the weight of the organic material is sufficient. Amounts down to as little as 00001 percent by weight may be effective in some cases.

lt is to be understood that the stabilizing effect of the phenolic compounds is considerably enhanced by con ventional synergists such as certain sulfides and polysulfides. The synergist is used in conventional amounts. For example, an amount of synergist from about 0.1 percent to about 1 percent by weight of the organic material to be stabilized is satisfactory but we prefer to use from 0.l percent to 0.5 percent by weight.

As sulfides there may be mentioned dialkylsulfides. particularly wherein the alkyl groups are long chain such as dodecyl groups since the lower dialkylsulfides are too volatile to be effective, di(substituted)- alkylsulfides particularly esters of bis-carboxyalkyl sulfides such as dilauryl, distearyl, ditridecyl, or dioctadecyl thiodipropionates or thiodibutyrates. dibenzylsulfide such as bis(Z-hydroxy-S-methylbenzyl)sulfide and bis(3-tert-butyl-2-hydroxy-S-methoxybenzyl)sulfide, diaryl sulfide, sulfides such as diphenyl sulfide, dicresyl sulfide, 2,2'-dihydroxy-5,5'dimethyl diphenyl sulfide, diphenyldisulfide, dialkyldithiophosphates such as bis(- diisopropyldithiophosphoryl)disulfide, and dialkyldithiophosphatomethylphenols.

It will further be understood that the organic material in addition to containing a stabilizing amount of the phenolic compound and a synergist may contain such other ingredients as other antioxidants, coloring agents, fillers, curing agents, etc.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following embodiments of this invention are shown for the purpose of illustrating the invention and demonstrate the best mode for practicing the invention. It will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as it is more precisely defined in the sub joined claims.

EXAMPLE 1 In a reaction vessel with a stirrer, condenser, thermometer, and dropping funnel, was placed a solution of 17 g of paraformaldehyde and 278 g of 2.6-di-pmethylbenzylphenol in 500 g of ethanol. To this stirred solution maintained under a nitrogen atmosphere at 40C. was added sulfuric acid in a dropwise manner until 250 g had been added, The mixture was stirred for lrzhours, cooled, and the solid filtered off. The product was washed with water, filtered, recrystalized from ethanol, and dried. After drying the product which was 4,- 4'-methylenebis( 2,6-di-p-methylbenzylphenol) was obtained in 83 percent yield and had a melting point of l23l24C.

EXAMPLE 2 Using the equipment of Example 1, 105 ml of sulfuric acid was admixed with 210 ml of ethanol. To this stirred solution maintained under a nitrogen atmosphere and at a temperature of 30C. was added 7 g of paraformaldehyde. At a temperature of about 50C. a mixture of 105 g of 2,6-dibenzylphenol in 60 ml of ethanol was added to the above stirred solution. The total admixture was maintained under a nitrogen atmosphere at about 4550C. for about an hour. The admixture was cooled and the solid filtered off. The product was washed with water, filtered, and air dried. The dried product was extracted with n-hexane, filtered, and recrystalized from ethanol. The product was 4,4- methylenebis( 2,6-dibenzylphenol) which had a melting point of l00-l02C.

EXAMPLE 3 Using the equipment of Example 1. 200 ml of sulfuric acid was admixed with 400 ml of ethanol. To this stirred solution maintained under a nitrogen atmosphere at 20-25C. was added a mixture of 36 g of paraformaldehyde and 636 g of 2,6-di(2"-ethylhexyllphenol. The reaction mixture was maintained under a nitrogen atmosphere at 2025C. overnight. Then the reaction mixture was extracted with 2 liters of n-hexane and 2 liters of water. The water was separated from the n-hexane fraction and the n-hexane fraction washed with 800 ml of water. The water was again separated from the n-hexane fraction and the fraction was dried with MgSO The MgSo, was removed by filtration from the n-hexane fraction and the n-hexane was stripped from the crude product. The unreacted 2,6-di(2"-ethylhexyl)phenol was removed from the crude product by distillation under a reduced pressure of 0.18 mm of Hg at temperatures up to 240C. The product was 4,4'-methylenebis[2,6-di(2"- ethylhexyllphenol].

EXAMPLE 4 Following the procedure of Example 2 but using two moles of 2,6-di(p-methoxybenzyl)phenol in place of the two moles of 2,6-dibenzylphenol, 4,4- methylenebis[ 2,6-di( p-methoxybenzyl )phenol ]was prepared.

EXAMPLE 5 Following the procedure of Example 3 but substituting two moles of 2,6-diisobutylphenol for the two moles of 2,6-di(2"-ethylhcxyl)phenol, 4,4'-methylenebis- (2,6-diisobutylphenol) was prepared.

EXAMPLE 6 The performance of several phenolic compounds as antioxidants for polypropylene was determined in the following tests:

In Test 1 an g sample of Hercules Pro-Fax 6501 polypropylene powder was mixed in a Brabender Plasticorder in which the mixing chamber was heated to about 200C. The material was mixed for 5 to l0 minutes until the polypropylene had a workable consistency. A sample of the material was then removed and molded into a 5 mil film. The one-inch diameter circles of the film were cut out and put into an oven maintained at 140C. After 1 hour in the oven, the sample crumbled.

ln Test 2, 0.24 g of dilaurylthiodipropionate was mixed with the 80 g of polypropylene powder and a sample tested for heat aging as in Test 1. The sample lasted for 70 hours before it crumbled.

The procedure of Test 1 was repeated in Test 3 except that 0.08 g of 4,4'-methy1enebis(2.6-di-tertbutylphenol) was added to the polypropylene powder. A 5 mil film sample tested as in Test 1 lasted for 16 hours before crumbling.

Test 4 was conducted like Test 2 except that 0.08 g of 4,4-methylenebis(2,6-di-tert-butylpheno1) was also incorporated into the polypropylene powder. The sample from this test lasted for 21 1 hours.

Test 5 was conducted similarly to Test 1 except that 0.08 g of 4.4'-methylenebis[2,6-di(2"- ethylhexyl)phenol] prepared in Example 3 was added to the polypropylene powder. The sample lasted for 16 hours.

In Test 6 the procedures of Test 2 was repeated except that 0.08 g of 4,4'-methylenebis[2,6-di(2"- ethylhexyl-phenol] prepared in Example 3 was also added to the polypropylene powder. The sample in this test lasted for 691 hours.

Test 7 was conducted like Test 1 except that 0.08 g of 4,4-methylenebis(2.6-diisobutylphenol) prepared in Example 5 was added to the polypropylene powder. The sample film from this test lasted 40 hours.

The method of Test 2 was repeated in Test 8 except that 0.08 g of 4,4'-methylenebis(2,6-diisobutylphenol) prepared in Example 5 was also added to the polypropylene powder. The sample lasted for 40 hours.

The procedure of Test l was repeated in Test 9 except that 0.08 g of 4,4'-methylenebis(2,6- dibenzylphenol) prepared in Example 2 was added to the polypropylene powder. A 5 mil sample tested as in Test 1 lasted for 73 hours before crumbling.

Test 10 was conducted like Test 2 except that 0.08 g of 4,4'-methylenebis(2,6-dibenzy1phenol) was also incorporated into the polypropylene powder. A sample from this test lasted for 837 hours before crumbling.

Test 11 was prepared like Test 1 except that 0.08 g of 4,4-methylenebis[2,6-di(p-methylbenzyl)phenol] was added to the polypropylene powder. The film from this test lasted 103 hours before crumbling.

Test 12 was conducted like Test 2 except that 0.08 g of 4,4'-methylenebis[2.6-di(p-methylbenzy1)phenol] was also incorporated into the polypropylene powder. A sample from this test lasted 915 hours before crumbling.

EXAMPLE 7 4.4'-Methylenehis[ 2.6-di( 2 "-ethylhexyl)pheno1] from Example 3 and 4,4-methylenebis(2,6-di-tertbutylphenol) were evaluated in this example as antioxidants for turbine oil. A modification of ASTM D943-IP157 was used. The following modifications were made: inches of electrolylic copper wire No. 14 Brown and Sharpe gage and 15 inches of lowmetalloid steel wire No. 16 Washburn and Moen gage were used to wind the mandrel; 150 ml of an unstabilized base oil provided by American Oil Company was used; oil temperature was held at C. during the test; and air was substituted for oxygen.

In Test 13, 0.63 g of 4,4'-methylenebis(2,6-di-tertbutylphenol) was added to the oil. Every 24 hours a 5-10 g sample of oil was removed from the oil tube. The acid number (mg KOH/g sample) of the sample was determined and the time required to reach an acid number of 2.0 was determined. In this test it took 5 days for the acid number to reach 2.0

Following the above procedure in Test 14 the effectiveness of 4.4'-methylenebis[2,6-di(2"- ethylhexy1)pheno1} in place of the 4,4-

methylenebis(2,6-di-tert-butylphenol) as a stabilizer for turbine oil was determined. In this test it took 2 days for the acid number of the oil to reach 2.0.

Test 15 was conducted like Test 13 except that 4,4- methylenebis(2,6-dibenzylphenol) was used in place of the 4.4'-methylenebis(2,6di-tert-butylphenol). In this test it took 2 days for the acid number of the oil to reach 2.0.

The above Examples clearly demonstrate the accomplishment of this invention. Examples 3 and 5 are preparations of 4,4-methylenebis(2.6-dialkylphenols) useful for comparison with the 4,4'-methylenebis(2,6- diaralkyphenols) prepared in Examples 1, 2, and 4. Examples l, 2, and 4 demonstrate the best mode for preparing the 4.4'-methylenebis(2,6-diaralkylphenols) of Formula 11.

The above examples clearly demonstrate the accomplishment of this invention. Examples l-3 demonstrate our preferred method for obtaining the phenolic compounds useful in our invention.

In Example 6 a comparison of Tests 9 and l l with Test 3, 5, and 7 clearly demonstrates the unexpected superiority of phenolic compounds of Formula 11 as antioxidants in polyropylene over 4,4-methylenebis(2,6- dialkylphenols). This superiority is even better demonstrated by a comparison of Tests 10 and 12 with Test 4, 6, and 8 wherein a conventional synergist is used with the antioxidant. Tests 1-8 inclusive are not embodiments of our invention but were prepared for the purposes of comparison with Tests 9-12 inclusive.

in Example 7 a comparison of Test 15 with Tests 13 and 14 shows that phenolic compounds of Formula 11 do not distinguish themselves as antioxidants in turbine oils in comparison with 4,4'-methylenebis(2,6- dialkylphenols). Tests 13 and 14 are not embodiments of our invention but were prepared to compare with the results of Example 4. The excellent ability of phenolic compounds of Formula 11 to stabilize polypropylene in Example 6 as compared to that of 4,4- methylenebis(2,6-dialkylphenols) is unexpected in view of their lackluster performance in Example 7 in turbine oil.

From the foregoing description we consider it to be clear that the present invention contributes a substantial benefit to the antioxidant art by providing a new and useful antioxidant for organic materials normally tending to undergo oxidative deterioration.

We claim:

1. A composition of the formula:

HO OH where X is alkoxy group containing from 1-13 carbon wherein R,, R R and R are aralkyl groups of the foL l t atoms. Owing struc X 5 2. The composition of claim 1 which is 4,4'

H methylenebis[2.6-di(o-ethoxybenzyi)phenol}. C 3. The composition of claim 1 which is 4,4-

methylenebis[2,6-di(p-methoxybenzyl)phenol]. 

1. A COMPOSITION OF THE FORMULA:
 2. The composition of claim 1 which is 4,4''-methylenebis(2,6-di(o-ethoxybenzyl)phenol).
 3. The composition of claim 1 which is 4,4''-methylenebis(2,6-di(p-methoxybenzyl)phenol). 